Apparatus for converting intermittent power to continuous power



Nov. 16, 1948. RR. HAYS APPARATUS FOR CONVERTING INT 2,454,058 ERMITTENT1 7 POWER TO CONTINUOUS POWER Filed Oct. 19, 1944 2 Sheets-Sheet lINVENTOR, Z? 1615. r

Nov. 16, 1948. R. R. HAYS APPARATUS FOR CONVERTING INTERMITTENT POWER TOCONTINUOUS POWER 2 Sheets-Sheet 2 Filed Oct. 19, 1944 INVENTOR, Zwre/fZ? iya".

Patented Nov. 16, 1948 2,454,053 APPARATUS FOR CONVERTING INTEBMIT- TENTPOWER TO CONTINUOUS POWER Russell R. Hays, Lawrence, Kans. ApplicationOctober 19, 1944, Serial No. 559,454 6 Claims. (01. 605"1) Thisinvention relates to method of and apparatus for converting intermittentpower to continuous power and more particularly to a process forobtaining continuous energy from intermittent winds; the main elementsof which are a giant windmill used to operate a multiple phase aircompressor, a subterranean compressed air reservoir in porous waterbearing rock, and an air motor operated by an airstream derived from thereser- Large windmills are not widely used at the present time for tworeasons. One, air currents are not consistent and therefore the powerdelivered by the windmill is not continuous. Two, the initial cost andmaintenance of large capacity reservoirs for storing the energy thusgenerated has not justified their installation. Among the reservoirswhich may be used are water tanks or ponds lying above the prime moverand providing .a hydrostatic head for its operation, battery units iordriving motors, and tanks for storing compressed air which may be usedfor driving air engines.

Smaller windmills for pumping water and char ing batteries, on the otherhand, are used extensively for the reason that the cost of installationis low and the small capacity reservoirs used are adequate for thepurposes served. The utility of large windmills is consequently seen toreside in the development of bigger rotors having a low initial cost inconjunction with the development of large capacity andinexpensivereservoirs for storing the energy generated by them.

In the present invention such utility is provided; first, by adaptingthe principles incorporated in lifting rotors or propellers to obtain adependable large span windmill having a low first cost; and, secondly,by utilizing porous water bearing rock strata and lenses lying atrelatively shallow depths to obtain sufficient compressed air storagespace at no cost other than installation.

Treating these elements individually and in the order of their use, thestructural problems arising when the conventional windmill rotor isincreased in size have their source in the gyroscopic forces transmittedto the rotor hub with sudden movement of the rotor in response tochanges in the direction of the wind; and, the fact that for the millhead carrying a vertically disposed rotor to pivot freely about avertical pivot carried at the top of the supporting structure, the upperportion of this structure must have substantially vertical sides andhence considerable thickness to provide the necessary structuralstrength.

the initial Both of these disadvantages are eliminated through theadaptation of rotors having tilting or flapping blades, as for instancethe two-bladed rotor illustrated in my co-pending application, SerialNo. 494,705, new Patent No. 2,369,048, issued February 6, 1945, for aDrop-center rotor. This rotor is characterized by opposite andinterconnected. blades being mounted for limited rocking movement aboutan axis transverse to the rotors axis of rotation. By reason of thismounting the rotor rocks or tilts about this transverse axis toautomatically equalize the air loads effective upon opposite blades,thereby increaslingithe smoothness of the rotor when operating in yaw. Afurther advantage of such a yieldable rotor mounting is that with suddenchanges in the direction of the wind, the gyroscopic forces arising inthe rotor in response to this change are not transmitted directly to therotor hub, which because of the yieldable nature of the rotor mountingacts to feather the blades with respect to their original plane ofrotation thereby providing a ,corrective rolling moment which more orless nullifies the gyroscopio moment.

Conversion of a lifting rotor to a windmill rotor is achieved'by turningthe blades over and increasing their pitch. Several such conversionshave been made the rotors tested as windmills. In this testing, apertinent fact uncovered was that the drop in efficiency when the rotorsplane of rotation was tilted from the vertical to as much 30 to thevertical was surprisingly small. The direct application of this findingwas that such rotors could be mounted at the apex of a pyramidal tower,thereby reducing the structure required to support the mill to about oneiourth that required for the same rotor when operated in a verticalplane. An added advantage was that with the rotor hub positioned closeto the vertical head pivot, it was now feasible to use a conventionalvane and coiled spring for pulling the rotor into the wind, and forautomatically decreasing its attack angle to the wind in response tomarked increases in the velocity of the latter.

Gearing the rotor to drive a multiple phase compressor mounted in thetop of the supporting tower and piping of the compressed air to an inputwell follows accepted procedure. Selection and preparation of theunderground storage rese r voir, however, calls for specialconsideration, At the present time, compressed air is used for drivingoil in stripper fields, and gas under pressure is forced back intoabandoned gas fields for storage, W'hile the process is broadly similarto these, the development of porouswater filled strata lying 3 atrelatively shallow depths as compressed air reservoirs is in no sensecompetitive with either, To begin with, oil and gas fields suitable forrepressuring are rarely found at depths less than 590 feet, and most ofthem lie considerably deeper. The original nature of these reservoirsalso prevents their use for compressed air storage, the retained gasesbeing capable of producing an explosive mixture, and with stripperfields migration of oil to lower pressure areas prevents maintenance ofthe input pressure.

For efiicient compressed air storage the strata used will preferably liebetween 200 feet and 590 feet beneath the surface. At these depthssurface structure is usually rather well reflected in sedimentary rocksso that it is not particularly difficult to locate the high point ofsmall domes or to choose strata lying level. Although individual sandlenses may be used for air storage, a highly porous strata of sandstoneor limestone containing either water or brine is highly preferable. Thereason is that water forced out of the domes or away from the input wellin a level strata exerts its original hydrostatic head against the imputair to maintain a substantially constant pressure within the reservoir,as opposed to the pressure gradient resultant to filling of a closedcontainer.

The use of highly porous and fluid flanked reservoirs which will providea more or less continuous pressure of the stored air regardless of itsvolume is of primary importance as regards the efiiciency of thewindmill. This is because the prevailing winds vary greatly in theirintensity, and it is desirable to utilize them through as wide a rangeas possible. Hence if the input pressure required increases markedly asthe reservoir fills, it follows that the starting torque required toovercome this pressure will increase by a like amount and consequentlythe mill would cease to operate in slower winds unless a complicatedgear shift mechanism were incorporated in the gearing.

The use of relatively shallow artesian formations is also desirablesince the compression of air becomes mechanically more difficult athigher pressures, requiring heavier and more expensive compressors. Thisinvolves an increase in the initial outlay as does the drilling andequipping of deeper wells.

The depth of a well is not in itself the determining factor in itssuitability as a reservoir, although in most localities it is indicativeof the minimum working pressure available. This latter is dependent uponthe bottom hole pressure of the water in the drill hole. This pressureis determined by the distance the water rises above the porous stratawhen drilled into. Hence if at a depth of 200 feet a water sand isencountered and the water rises quickly to within 50 feet of thesurface, its bottom hole pressure is in the neighborhood of 65 pounds.In short, the air pressure required to drive the water away from thedrill hole will need to be greater than this.

The next factor to be considered is the permeability of the formation.This is initially increased by shooting or acidizing the drill hole toincrease the drainage face. Beyond this point it is predeterminedlargely by the porosity of the strata, and is the factor limiting therate of withdrawal from the reservoir. This rate is readily determinedby pumping air into the reservoir and taking pressure readings at thewell head as an escape valve passing through a gas meter is slowlyopened. When the pressure, in the instance cited, begins to drop below65 pounds, the natural rate of the reservoir is being exceeded, and towithdraw quate clearance with respect 4 air more rapidly represents aloss in efficiency due to the limited porosity of the rock.

This natural rate of the reservoir is also reflected by an of inputl3l"=3SSl.1l'e above 65 pounds as the rate of ut in d. It becomesevident therefore that the size of the compressor and windmill unitwhich can be used most advantageously with any natural reservoir islimited by this factor. The point to be made is that for family use orsmall communities, there are numerous shallow rock reservoirs having ahigh enough natural rate to make their use economically practical forsupplying continuous power when used in conjunction with windmillpowered compressors,

Accordingly, the object of this invention is broadly to provide adependable windmill of larger span than those commonly used for thepurpose of forcing compressed air into a natural rock reservoir, fromwhich it may be withdrawn, continuously at a constant rate and pressurefor the operation of an air engine or other air operated machinery.

Another object is the provision of an improved rotor for a windmillwhich is mounted for limited rocking about an axis transverse to itsaxis of rotation.

Yet another object is the provision of a windmill rotor of large sizemounted for limited roclo ing about an aXis transverse to its axis ofrotation, in which the axis of rotation is tilted up through an angle ofabout 30 to the horizontal in order that the rotor may be mounted at theapex of a pyramidal tower and at the same time have adeto the legs ofthis tower.

Another object is the provision of a multiple phase compressor geareddirectly to such an improved rotor, a line for cooling and conductingthe compressed air through a filter for removing dust and other foreignmaterial, a check valve on the line intermediate filter the input tubingleading to a porous rock structure.

Another object is the provision of a subsurface air reservoir in aporous strata initially filled with water, an air line leading from thisreservoir to the surface where it is fitted with a regulator andrestricted orifice permitting a continuous flow of air from thereservoir at the latters natural rate to drive an air engine or otherair activated mechanism. I

Ancillary objectives such as the use of a conven tional vane governor toautomatically throw the rotor into and out of the wind, the use ofsafety Valves on the air line to prevent heaving of the rocks lyingbetween the reservoir and the surface, and other accessories to theprocess used will become clearer from reading the following descriptionin conjunction with the accompanying drawings in which:

Figure 1 is a diagrammatic sketch showing the plan of installation of awindmill and subsurface reservoir unit such as that embodied in thisinvention, and

Figure 2 is an enlarged View in side elevation of the rotor head andcompressor of the windmill shown in Fig. 1, with parts partly brokenaway.

Referring to the figures, the windmill H] has a tower with legs I lforming a pyramidal structure topped by the head member M which containsconcentrically disposed bearing seats IS in which the lower extension llof the mill head 18 is mounted for free turning movement about avertical axis AA, being retained in the head member M by means ofadjustable nut 20 and washer 19. The mill head 18 forms a case carryingthe rotor drive shaft 22 in bearings 24 and 25 in a canted positionrelative to the horizontal in which its axis of rotation B--B intersectsthe vertical mill head axis A--A and makes an angle E of approximately60 degrees with it.

The inner end of the rotor shaft 22 carries the driving gear 25 whichmeshes with the compressor gear 21 carried on the shaft 29concentrically disposed within the mill head extension 11 where it isretained by lock bearing 32 having setscrew 33. The outer end or" theshaft 22 carries the rotor hub mounting 35 in which are fixed transverserocking pins 36 upon which the rotor hub 40 is mounted by means oftransverse bearings carried in the hub extensions 42. The hub 40 is madeof slightly yieldable material such as spring steel and the blades 45and 41 mounted on it by butts 44 and 45 respectively are pre-coned sothat the center of mass of the rotor lies substantially on the rockingaxis carried by pin 35. Otherwise the plan of the blades followsconventional practice either as regards windmills or lifting rotors asis described more in detail in said Patent No. 2,369,048 for aDrop-center rotor. Rocking of the rotor about the pin 36 is limited tomovement through angles C and D of plus and minus 10 approximatel to therotors mean plane of rotation PP by means of brackets 4i in the bottomof the hub structure 40 which carry resilient pads or dampers 39 whichloosely contact the rotor shaft extension 38 when the rotor operates inplane P-P.

The back end of the mill head is extends as brackets and 52 carrying thevertical pin 53 upon which is mounted the nose piece 55 of the vane 58.Arms 58 and 51 of the nose piece extend away from the mill head to carrythe vertically disposed vane 58. The stop 54 at the front of thenosepiece 55 prevents swinging of the vane out of a vertical plane inalignment with the axis 3-13 in one direction, and the coiled spring 80mounted on bracket 59 carried by the vane arm 56 and bracket 6| carriedby the arm 63 extending laterally i'rom the millhead, provides a springtension preventing the vane from swinging out of alignment in the otherdirection. This is the ordinary spring governor for windmills, thetorque created by the rotor tending to turn the mill head in a directionopposed to the tension of spring Ell, and out of the wind, whereas thevane exerts a tension on the spring 60 tending to pull it back into thewind.

The vertical drive shaft 29 which extends down ward from the mill headgear box is coupled to the crankshaft of the multiple phase compressorby means of coupling 12 carrying set screws 13 and 14. The crankcase 16of the compressor is solidly affixed to the cross-members 12 of the milltower H, and has at least two cylinder-s, one of which 19 compresses theair in the first stage, and the other 18 in the second phase as is wellknown in the art. A conduit 80 connects the exhaust port of the cylinder18 with the air line 82 which extends down to the ground into groundline 83 which feeds into the filter or washer 90 adjacent the input wellH6. The outlet line 92 from the filter 90 carries the check valve 93which allows down-well movement of the air from the filter but preventsits return, consequently the air from the compressor passes from thecheck valve 93 into the well tubing 95. Tubing 95 extends down into thedrill hole and into the shot hole H4 of the porous strata of thereservoir. Just above the shot hole a plate packer I I2 fills the drillhole 6 and provides a seat for solidly fixing the input tubing 95 intothe drill hole by cement H l.

The upper end of the input tubing continues into the line 96 carryingthe pressure guage 98 and the safety valve or pop-off 99 which is set toopen when the pressure in the line becomes approximately twice that ofthe rock pressure of the strata being used as a reservoir, thereby preventing any danger of heaving. The end of the line 96 passes into thepressure regulator I08 which is set approximately at the reservoirsinitial bottom hole pressure, and the outlet line H32 passes through thechoke or reduced orifice 103 which reduces the volume to the naturalrate of the input well or less depending upon the requirements of theinstallation before the air passes into the air turbine I04 which drivesthe generator H16 through the coupling I05 to provide a continuous flowof electricity into lines I08.

In operation the rotor 40 is unbraked by the release of a conventionalbrake and throwout mechanism (not shown) whereupon'the vane 58 acts toswing it into a position transverse to the relative airstream. Uponbeing turned by the wind it supplies a torque through the gears 26 and21 and shafts 22 and 29 respectively to the compressor 15. Thecompressed air from the compressor passes through the variousaccessories and down the input line 55 to the face of the shot hole I Min the porous strata l l5. Since the pressure of the compressed air isgreater than the bottom hole pressure exerted by the water in theformation it has the effect of forcing the water away from the drillhole and replacing it in the small openings thus vacated. A large numberof factors have bearing upon the rapidity with which this can be done,and consequently the normal rate of every reservoir will vary. Wherewater filled gravels comprise the strata used, this rate will be veryhigh, whereas with fine grained silts or sandstones it will berelatively low.

The same factor will control the rate of up-dip migration of the air inthe strata in cases where small domes are not used as reservoirs. Thegeneral picture, however, is one of air replacing water in the porousstrata H5, and driving back the water into the flanks 1 it. Since thesurface drainage of such a strata normally extends over a very greatarea relative to the volume of the reservoir, this drainage lyingapproximately at the height to which the water initially rises in thedrill hole, very little permanent migration of the water can occur, thisbeing illustrated by heavy pumping of wells in such strata having nopermanent effect in lowering the water level of the formation. As thesewells refill when pumping is discontinued, in a like fashion thehydrostatic head of the water at the flanks of the reservoir acts todrive the air back into the line 95.

The general principle involved is consequently seen to be one of therate or" input from the compressor into the reservoir being many timesgreater than the rate of withdrawal through the regulator me and reducedorifice I03. Consequently, once the persistency and velocity of theprevailing winds in any locality is known, it becomes possible toestimate with reasonable accuracy the reservoir capacity required tosupply a continuous airstream to the air engine I04 at the natural rateof the reservoir or less, and accordingly these factors will dictate themaximum windmill installation required.

Numerous adaptation and changes may be made in the relative size andarrangement of parts without departure from the general nature of the,process described.

Having thus described the invention, what I claim as newand desire to besecured by Letters Patents is:

1. In combination, an air compressor driven by a-varying source ofpower, a conduit connecting said compressor with a subsurface waterbearing porous rock strata adapted to receive compressed air from saidair compressor and to exert a hydrostatic pressure on said air wherebythe density of said air remains substantially constant, and a pressurecontrolled conduit communicating with said porous rock strata whereby asubstantially even flow of energy is maintained therefrom.

2. In combination, an air compressor driven by a windmill having a rotormounted for limited rocking movement about an axis transverse to therotors axis of rotation, a subsurface compressed air chamber situated ina porous water bearing strata adapted to receive compressed air fromsaid air compressor, a motor, and a pressure controlled conduit wherebya substantially even flow of energy is delivered from said subsurfacecompressed air chamber to said motor.

3. Hydraulic means for converting the energy of intermittent winds tocontinuous power, comprising in combination with a wind rotoroperatively associated with an air compressor, a conduit connecting saidcompressor with a sealed artesian reservoir, and a restricted constantpressure outlet from said conduit intermediate said compressor and saidreservoir.

4. Hydraulic means for converting the energy of intermittent winds tocontinuous power, comprisin in combination with a wind rotor operativelyassociated with an air compressor, a conduit connecting said compressorwith a sealed ar tesian reservoir, and a restricted surface outlet onsaid conduit opening into a regulator maintaining the outlet linepressure slightly below that of said reservoir, whereby said reservoirsupplies a continuous airstream to said restricted outlet at those timeswhen the wind rotor is not operating said air compressor, the samepressures as when said compressor is in operation.

5. Hydraulic means for converting intermittent power'to continuouspower, comprising in combination with an intermittent source of power,

and at substantially 8 an' air compressor operatively associatedtherewith, a-conduit leading therefrom and communicating with a sealedartesian reservoir, pneumatic means; including an airstream compressedto pressures in excess of the reservoir pressure for forcing thecontained fluid away from the conduit opening to said reservoir,hydraulic means including the natural hydrostatic head of said containedfluid for drivin said pneumatic means back into said conduit-in responseto pressure reduction therein, and a restricted constant pressure outleton said conduit for supplying a continuous high pressure airstream.

6. Hydraulic means for converting intermittent power to continuouspower, comprising in combination with an intermittent source of power,an air compressor operatively associated therewith, a conduit leadingtherefrom and communicating with a sealed artesian reservoir, pneumaticmeans including an airstream compressed to pressures in excess of thereservoir pressure for force ing the contained fluid away from theconduit opening to said reservoir, hydraulic means including the naturalhydrostatic head of said ,contained fluid for driving said pneumaticmeans back into said conduit in response to pressure reduction therein,and a restricted constant pressure outlet from said conduit forsupplying a continuous high pressure airstream, whereby an air engine isoperated continuously.

RUSSELL R. HAYS.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 254,303 GeringFeb. 28, 1882 320,482 Leavitt June 23, 1885 543,462 Bramwell July 30,1895 607,151 Wichmann July 12, 1898 1,035,431 Ericson Aug. 13, 19121,679,417 Garnier Aug. '7, 1928 2,116,023 Gwidt May 3, 1938 2,369,048Hays Feb. 6, 1945 FOREIGN PATENTS Number Country Date 601,536 GermanyOct. 1, 1934

